Patchwork [03/21] qom: Add core type system

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Submitter Anthony Liguori
Date July 25, 2011, 1:44 a.m.
Message ID <1311558293-5855-4-git-send-email-aliguori@us.ibm.com>
Download mbox | patch
Permalink /patch/106601/
State New
Headers show

Comments

Anthony Liguori - July 25, 2011, 1:44 a.m.
This patch implements the basic type system used by QEMU Object Model.  This
infrastructure supports the registration of classes and instantiation of
objects through a generic factory interface.  Classes support polymophism and
single inheritance.

Interfaces can also be used to approximate multiple inheritance.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
---
 Makefile.qom        |    4 +
 Qconfig             |    1 +
 configure           |    2 +-
 include/qemu/type.h |  513 ++++++++++++++++++++++++++++++++++++++++++++++++++
 qom/Makefile        |    1 +
 qom/Qconfig         |    6 +
 qom/type.c          |  523 +++++++++++++++++++++++++++++++++++++++++++++++++++
 7 files changed, 1049 insertions(+), 1 deletions(-)
 create mode 100644 include/qemu/type.h
 create mode 100644 qom/Makefile
 create mode 100644 qom/Qconfig
 create mode 100644 qom/type.c

Patch

diff --git a/Makefile.qom b/Makefile.qom
index 1b06970..34f1f91 100644
--- a/Makefile.qom
+++ b/Makefile.qom
@@ -9,3 +9,7 @@  config-qom.mak: $(SRC_PATH)/Qconfig $(QCONFIGS)
 
 include $(SRC_PATH)/qapi/Makefile
 common-obj-y += $(addprefix qapi/,$(qapi-obj-y))
+
+include $(SRC_PATH)/qom/Makefile
+common-obj-y += $(addprefix qom/,$(qom-obj-y))
+
diff --git a/Qconfig b/Qconfig
index cdf8f6c..889dfa6 100644
--- a/Qconfig
+++ b/Qconfig
@@ -1 +1,2 @@ 
 source qapi/Qconfig
+source qom/Qconfig
diff --git a/configure b/configure
index 600da9b..93e5e97 100755
--- a/configure
+++ b/configure
@@ -3516,7 +3516,7 @@  DIRS="$DIRS pc-bios/spapr-rtas"
 DIRS="$DIRS roms/seabios roms/vgabios"
 DIRS="$DIRS fsdev ui"
 DIRS="$DIRS qapi"
-DIRS="$DIRS qga"
+DIRS="$DIRS qga qom"
 FILES="Makefile tests/Makefile"
 FILES="$FILES tests/cris/Makefile tests/cris/.gdbinit"
 FILES="$FILES pc-bios/optionrom/Makefile pc-bios/keymaps"
diff --git a/include/qemu/type.h b/include/qemu/type.h
new file mode 100644
index 0000000..170f485
--- /dev/null
+++ b/include/qemu/type.h
@@ -0,0 +1,513 @@ 
+/*
+ * QEMU Object Model
+ *
+ * Copyright IBM, Corp. 2011
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef QEMU_TYPE_H
+#define QEMU_TYPE_H
+
+#include "qemu-common.h"
+#include <glib.h>
+
+#define MAX_ID (32 + 1)
+
+typedef uint64_t Type;
+
+typedef struct TypeClass TypeClass;
+typedef struct TypeInstance TypeInstance;
+typedef struct TypeInfo TypeInfo;
+
+typedef struct InterfaceClass InterfaceClass;
+typedef struct Interface Interface;
+typedef struct InterfaceInfo InterfaceInfo;
+
+/**
+ * @TypeClass:
+ *
+ * The base for all classes.  The only thing that @TypeClass contains is an
+ * integer type handle.
+ */
+struct TypeClass
+{
+    /**
+     * @type the handle of the type for a class
+     */
+    Type type;
+};
+
+/**
+ * @TypeInstance:
+ *
+ * The base for all objects.  The first member of this object is a pointer to
+ * a @TypeClass.  Since C guarantees that the first member of a structure
+ * always begins at byte 0 of that structure, as long as any sub-object places
+ * its parent as the first member, we can cast directly to a @TypeInstance.
+ *
+ * As a result, @TypeInstance contains a reference to the objects type as its
+ * first member.  This allows identification of the real type of the object at
+ * run time.
+ *
+ * @TypeInstance also contains a list of @Interfaces that this object
+ * implements.
+ */
+struct TypeInstance
+{
+    /**
+     * @class the type of the instantiated object.
+     */
+    TypeClass *class;
+
+    /**
+     * @id the name of the object
+     */
+    char id[MAX_ID];
+
+    /**
+     * @interfaces a list of @Interface objects implemented by this object
+     */
+    GSList *interfaces;
+};
+
+/**
+ * @TypeInfo:
+ *
+ */
+struct TypeInfo
+{
+    /**
+     * @name the name of the type
+     */
+    const char *name;
+
+    /**
+     * @parent the name of the parent type
+     */
+    const char *parent;
+
+    /**
+     * Instance Initialization
+     *
+     * This functions manage the instance construction and destruction of a
+     * type.
+     */
+
+    /**
+     * @instance_size the size of the object (derivative of @TypeInstance).  If
+     * @instance_size is 0, then the size of the object will be the size of the
+     * parent object.
+     */
+    size_t instance_size;
+
+    /**
+     * @instance_init
+     *
+     * This function is called to initialize an object.  The parent class will
+     * have already been initialized so the type is only responsible for
+     * initializing its own members.
+     */
+    void (*instance_init)(TypeInstance *obj);
+
+    /**
+     * @instance_finalize
+     *
+     * This function is called during object destruction.  This is called before
+     * the parent @instance_finalize function has been called.  An object should
+     * only free the members that are unique to its type in this function.
+     */
+    void (*instance_finalize)(TypeInstance *obj);
+
+    /**
+     * @abstract
+     *
+     * If this field is true, then the class is considered abstract and cannot
+     * be directly instantiated.
+     */
+    bool abstract;
+
+    /**
+     * Class Initialization
+     *
+     * Before an object is initialized, the class for the object must be
+     * initialized.  There is only one class object for all instance objects
+     * that is created lazily.
+     *
+     * Classes are initialized by first initializing any parent classes (if
+     * necessary).  After the parent class object has initialized, it will be
+     * copied into the current class object and any additional storage in the
+     * class object is zero filled.
+     *
+     * The effect of this is that classes automatically inherit any virtual
+     * function pointers that the parent class has already initialized.  All
+     * other fields will be zero filled.
+     *
+     * After this initial copy, @base_init is invoked.  This is meant to handle
+     * the case where a class may have a dynamic field that was copied via
+     * a shallow copy but needs to be deep copied.  @base_init is called for
+     * each parent class but not for the class being instantiated.
+     *
+     * Once all of the parent classes have been initialized and their @base_init
+     * functions have been called, @class_init is called to let the class being
+     * instantiated provide default initialize for it's virtual functions.
+     */
+
+    /**
+     * @class_size the size of the class object (derivative of @TypeClass) for
+     * this object.  If @class_size is 0, then the size of the class will be
+     * assumed to be the size of the parent class.  This allows a type to avoid
+     * implementing an explicit class type if they are not adding additional
+     * virtual functions.
+     */
+    size_t class_size;
+
+    /**
+     * @base_init
+     *
+     * This function is called after memcpy()'ing the base class into the new
+     * class to reinitialize any members that require deep copy.
+     */
+    void (*base_init)(TypeClass *klass);
+
+    /**
+     * @base_finalize
+     *
+     * This function is called during a class's destruction and is meant to
+     * allow any dynamic parameters allocated by @base_init to be released.
+     */
+    void (*base_finalize)(TypeClass *klass);
+
+    /**
+     * @class_init
+     *
+     * This function is called after all parent class initialization has occured
+     * to allow a class to set its default virtual method pointers.  This is
+     * also the function to use to override virtual methods from a parent class.
+     */
+    void (*class_init)(TypeClass *klass);
+
+    /**
+     * @class_finalize
+     *
+     * This function is called during class destruction and is meant to release
+     * and dynamic parameters allocated by @class_init.
+     */
+    void (*class_finalize)(TypeClass *klass);
+
+    /**
+     * Interfaces
+     *
+     * Interfaces allow a limited form of multiple inheritance.  Instances are
+     * similar to normal types except for the fact that are only defined by
+     * their classes and never carry any state.  You can cast an object to one
+     * of its @Interface types and vice versa.
+     */
+
+    /**
+     * @interfaces the list of interfaces associated with this type.  This
+     * should point to a static array that's terminated with a zero filled
+     * element.
+     */
+    InterfaceInfo *interfaces;
+};
+
+/**
+ * @TYPE_INSTANCE
+ *
+ * Converts an object to a @TypeInstance.  Since all objects are @TypeInstances,
+ * this function will always succeed.
+ */
+#define TYPE_INSTANCE(obj) \
+    ((TypeInstance *)(obj))
+
+/**
+ * @TYPE_CHECK
+ *
+ * A type safe version of @type_dynamic_cast_assert.  Typically each class will
+ * define a macro based on this type to perform type safe dynamic_casts to
+ * this object type.
+ *
+ * If an invalid object is passed to this function, a run time assert will be
+ * generated.
+ */
+#define TYPE_CHECK(type, obj, name) \
+    ((type *)type_dynamic_cast_assert((TypeInstance *)(obj), (name)))
+
+/**
+ * @TYPE_CLASS_CHECK
+ *
+ * A type safe version of @type_check_class.  This macro is typically wrapped
+ * by each type to perform type safe casts of a class to a specific class type.
+ */
+#define TYPE_CLASS_CHECK(class, obj, name) \
+    ((class *)type_check_class((TypeClass *)(obj), (name)))
+
+/**
+ * @TYPE_GET_CLASS
+ *
+ * This function will return a specific class for a given object.  Its generally
+ * used by each type to provide a type safe macro to get a specific class type
+ * from an object.
+ */
+#define TYPE_GET_CLASS(class, obj, name) \
+    TYPE_CLASS_CHECK(class, type_get_class(TYPE_INSTANCE(obj)), name)
+
+/**
+ * @Interface:
+ *
+ * The base for all Interfaces.  This is a subclass of TypeInstance.  Subclasses
+ * of @Interface should never have an instance that contains anything other than
+ * a single @Interface member.
+ */ 
+struct Interface
+{
+    /**
+     * @parent base class
+     */
+    TypeInstance parent;
+
+    /* private */
+
+    /**
+     * @obj a pointer to the object that implements this interface.  This is
+     * used to allow casting from an interface to the base object.
+     */
+    TypeInstance *obj;
+};
+
+/**
+ * @InterfaceClass:
+ *
+ * The class for all interfaces.  Subclasses of this class should only add
+ * virtual methods.
+ */
+struct InterfaceClass
+{
+    /**
+     * @parent_class the base class
+     */
+    TypeClass parent_class;
+};
+
+/**
+ * @InterfaceInfo:
+ *
+ * The information associated with an interface.
+ */
+struct InterfaceInfo
+{
+    /**
+     * @type the name of the interface
+     */
+    const char *type;
+
+    /**
+     * @interface_initfn is called during class initialization and is used to
+     * initialize an interface associated with a class.  This function should
+     * initialize any default virtual functions for a class and/or override
+     * virtual functions in a parent class.
+     */
+    void (*interface_initfn)(TypeClass *class);
+};
+
+#define TYPE_INTERFACE "interface"
+#define INTERFACE(obj) TYPE_CHECK(Interface, obj, TYPE_INTERFACE)
+
+/**
+ * @type_new:
+ *
+ * This function will initialize a new object using heap allocated memory.  This
+ * function should be paired with @type_delete to free the resources associated
+ * with the object.
+ *
+ * @typename: The name of the type of the object to instantiate
+ *
+ * @id:       The id of the object.  This must be unique.
+ *
+ * Returns:   The newly allocated and instantiated object.
+ *
+ */
+TypeInstance *type_new(const char *typename, const char *id);
+
+/**
+ * @type_delete:
+ *
+ * Finalize an object and then free the memory associated with it.  This should
+ * be paired with @type_new to free the resources associated with an object.
+ *
+ * @obj:  The object to free.
+ *
+ */
+void type_delete(TypeInstance *obj);
+
+/**
+ * @type_initialize:
+ *
+ * This function will initialize an object.  The memory for the object should
+ * have already been allocated.
+ *
+ * @obj:      A pointer to the memory to be used for the object.
+ *
+ * @typename: The name of the type of the object to instantiate
+ *
+ * @id:       The id of the object.  This must be unique.
+ *
+ */
+void type_initialize(void *obj, const char *typename, const char *id);
+
+/**
+ * @type_finalize:
+ *
+ * This function destroys and object without freeing the memory associated with
+ * it.
+ *
+ * @obj:
+ *
+ */
+void type_finalize(void *obj);
+
+/**
+ * @type_dynamic_cast:
+ *
+ * This function will determine if @obj is-a @typename.  @obj can refer to an
+ * object or an interface associated with an object.
+ *
+ * @obj:       The object to cast.
+ *
+ * @typename:  The @typename
+ *
+ * Returns:
+ *
+ */
+TypeInstance *type_dynamic_cast(TypeInstance *obj, const char *typename);
+
+/**
+ * @type_dynamic_cast_assert:
+ *
+ * @obj:
+ *
+ * @typename:
+ *
+ * Returns:
+ *
+ */
+TypeInstance *type_dynamic_cast_assert(TypeInstance *obj, const char *typename);
+
+/**
+ * @type_is_type:
+ *
+ * @obj:
+ *
+ * @typename:
+ *
+ * Returns:
+ *
+ */
+bool type_is_type(TypeInstance *obj, const char *typename);
+
+/**
+ * @type_get_class:
+ *
+ * @obj:
+ *
+ * Returns:
+ *
+ */
+TypeClass *type_get_class(TypeInstance *obj);
+
+/**
+ * @type_get_id:
+ *
+ * @obj:
+ *
+ * Returns:
+ *
+ */
+const char *type_get_id(TypeInstance *obj);
+
+/**
+ * @type_get_type:
+ *
+ * @obj:
+ *
+ * Returns:
+ */
+const char *type_get_type(TypeInstance *obj);
+
+/**
+ * @type_get_super:
+ *
+ * @obj:
+ *
+ * Returns:
+ */
+TypeClass *type_get_super(TypeInstance *obj);
+
+/**/
+
+/**
+ * @type_register_static:
+ *
+ * @info:
+ *
+ * Returns:
+ */
+Type type_register_static(const TypeInfo *info);
+
+/**
+ * @type_find_by_id:
+ *
+ * @id:
+ *
+ * Returns:
+ *
+ */
+TypeInstance *type_find_by_id(const char *id);
+
+/**
+ * @type_check_class:
+ *
+ * @obj:
+ *
+ * @typename:
+ *
+ * Returns:
+ */
+TypeClass *type_check_class(TypeClass *obj, const char *typename);
+
+/**
+ * @type_get_by_name:
+ *
+ * @name:
+ *
+ * Returns:
+ */
+Type type_get_by_name(const char *name);
+
+/**
+ * @type_get_name:
+ *
+ * @type:
+ *
+ * Returns:
+ */
+const char *type_get_name(Type type);
+
+/**
+ * @type_foreach:
+ *
+ * @enumfn:
+ *
+ * @opaque:
+ *
+ */
+void type_foreach(void (*enumfn)(TypeInstance *obj, void *opaque),
+                  void *opaque);
+
+#endif
diff --git a/qom/Makefile b/qom/Makefile
new file mode 100644
index 0000000..838054f
--- /dev/null
+++ b/qom/Makefile
@@ -0,0 +1 @@ 
+qom-obj-$(CONFIG_QOM) += type.o
diff --git a/qom/Qconfig b/qom/Qconfig
new file mode 100644
index 0000000..16660b4
--- /dev/null
+++ b/qom/Qconfig
@@ -0,0 +1,6 @@ 
+config QOM
+       bool "QEMU Object Model Support"
+       default y
+       depends on QAPI
+       help
+         This is the core object model used by QEMU.  If in doubt, say y here.
diff --git a/qom/type.c b/qom/type.c
new file mode 100644
index 0000000..28e8114
--- /dev/null
+++ b/qom/type.c
@@ -0,0 +1,523 @@ 
+/*
+ * QEMU Object Model
+ *
+ * Copyright IBM, Corp. 2011
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu/type.h"
+#include <glib.h>
+
+#define MAX_INTERFACES 32
+
+typedef struct InterfaceImpl
+{
+    const char *parent;
+    void (*interface_initfn)(TypeClass *class);
+    Type type;
+} InterfaceImpl;
+
+typedef struct TypeImpl
+{
+    const char *name;
+    Type type;
+
+    size_t class_size;
+
+    size_t instance_size;
+
+    void (*base_init)(TypeClass *klass);
+    void (*base_finalize)(TypeClass *klass);
+
+    void (*class_init)(TypeClass *klass);
+    void (*class_finalize)(TypeClass *klass);
+
+    void (*instance_init)(TypeInstance *obj);
+    void (*instance_finalize)(TypeInstance *obj);
+
+    bool abstract;
+
+    const char *parent;
+
+    TypeClass *class;
+
+    int num_interfaces;
+    InterfaceImpl interfaces[MAX_INTERFACES];
+} TypeImpl;
+
+static int num_types = 1;
+static TypeImpl type_table[128];
+
+Type type_register_static(const TypeInfo *info)
+{
+    Type type = num_types++;
+    TypeImpl *ti;
+
+    ti = &type_table[type];
+
+    assert(info->name != NULL);
+
+    ti->name = info->name;
+    ti->parent = info->parent;
+    ti->type = type;
+
+    ti->class_size = info->class_size;
+    ti->instance_size = info->instance_size;
+
+    ti->base_init = info->base_init;
+    ti->base_finalize = info->base_finalize;
+
+    ti->class_init = info->class_init;
+    ti->class_finalize = info->class_finalize;
+
+    ti->instance_init = info->instance_init;
+    ti->instance_finalize = info->instance_finalize;
+
+    ti->abstract = info->abstract;
+
+    if (info->interfaces) {
+        int i;
+
+        for (i = 0; info->interfaces[i].type; i++) {
+            ti->interfaces[i].parent = info->interfaces[i].type;
+            ti->interfaces[i].interface_initfn = info->interfaces[i].interface_initfn;
+            ti->num_interfaces++;
+        }
+    }
+
+    return type;
+}
+
+static Type type_register_anonymous(const TypeInfo *info)
+{
+    Type type = num_types++;
+    TypeImpl *ti;
+    char buffer[32];
+    static int count;
+
+    ti = &type_table[type];
+
+    snprintf(buffer, sizeof(buffer), "<anonymous-%d>", count++);
+    ti->name = qemu_strdup(buffer);
+    ti->parent = qemu_strdup(info->parent);
+    ti->type = type;
+
+    ti->class_size = info->class_size;
+    ti->instance_size = info->instance_size;
+
+    ti->base_init = info->base_init;
+    ti->base_finalize = info->base_finalize;
+
+    ti->class_init = info->class_init;
+    ti->class_finalize = info->class_finalize;
+
+    ti->instance_init = info->instance_init;
+    ti->instance_finalize = info->instance_finalize;
+
+    if (info->interfaces) {
+        int i;
+
+        for (i = 0; info->interfaces[i].type; i++) {
+            ti->interfaces[i].parent = info->interfaces[i].type;
+            ti->interfaces[i].interface_initfn = info->interfaces[i].interface_initfn;
+            ti->num_interfaces++;
+        }
+    }
+
+    return type;
+}
+
+static TypeImpl *type_get_instance(Type type)
+{
+    assert(type != 0);
+    assert(type < num_types);
+
+    return &type_table[type];
+}
+
+Type type_get_by_name(const char *name)
+{
+    int i;
+
+    if (name == NULL) {
+        return 0;
+    }
+
+    for (i = 1; i < num_types; i++) {
+        if (strcmp(name, type_table[i].name) == 0) {
+            return i;
+        }
+    }
+
+    return 0;
+}
+
+static void type_class_base_init(TypeImpl *base_ti, const char *typename)
+{
+    TypeImpl *ti;
+
+    if (!typename) {
+        return;
+    }
+
+    ti = type_get_instance(type_get_by_name(typename));
+
+    type_class_base_init(base_ti, ti->parent);
+
+    if (ti->base_init) {
+        ti->base_init(base_ti->class);
+    }
+}
+
+static size_t type_class_get_size(TypeImpl *ti)
+{
+    if (ti->class_size) {
+        return ti->class_size;
+    }
+
+    if (ti->parent) {
+        return type_class_get_size(type_get_instance(type_get_by_name(ti->parent)));
+    }
+
+    return sizeof(TypeClass);
+}
+
+static void type_class_interface_init(TypeImpl *ti, InterfaceImpl *iface)
+{
+    TypeInfo info = {
+        .instance_size = sizeof(Interface),
+        .parent = iface->parent,
+        .class_size = sizeof(InterfaceClass),
+        .class_init = iface->interface_initfn,
+        .abstract = true,
+    };
+
+    iface->type = type_register_anonymous(&info);
+}
+
+static void type_class_init(TypeImpl *ti)
+{
+    size_t class_size = sizeof(TypeClass);
+    int i;
+
+    if (ti->class) {
+        return;
+    }
+
+    ti->class_size = type_class_get_size(ti);
+
+    ti->class = qemu_malloc(ti->class_size);
+    ti->class->type = ti->type;
+
+    if (ti->parent) {
+        TypeImpl *ti_parent;
+
+        ti_parent = type_get_instance(type_get_by_name(ti->parent));
+
+        type_class_init(ti_parent);
+
+        class_size = ti_parent->class_size;
+        assert(ti_parent->class_size <= ti->class_size);
+
+        memcpy((void *)ti->class + sizeof(TypeClass),
+               (void *)ti_parent->class + sizeof(TypeClass),
+               ti_parent->class_size - sizeof(TypeClass));
+    }
+
+    memset((void *)ti->class + class_size, 0, ti->class_size - class_size);
+
+    type_class_base_init(ti, ti->parent);
+
+    for (i = 0; i < ti->num_interfaces; i++) {
+        type_class_interface_init(ti, &ti->interfaces[i]);
+    }
+
+    if (ti->class_init) {
+        ti->class_init(ti->class);
+    }
+}
+
+static void type_instance_interface_init(TypeInstance *obj, InterfaceImpl *iface)
+{
+    TypeImpl *ti = type_get_instance(iface->type);
+    Interface *iface_obj;
+    static int count;
+    char buffer[32];
+
+    snprintf(buffer, sizeof(buffer), "__anonymous_%d", count++);
+    iface_obj = INTERFACE(type_new(ti->name, buffer));
+    iface_obj->obj = obj;
+
+    obj->interfaces = g_slist_prepend(obj->interfaces, iface_obj);
+}
+
+static void type_instance_init(TypeInstance *obj, const char *typename)
+{
+    TypeImpl *ti = type_get_instance(type_get_by_name(typename));
+    int i;
+
+    if (ti->parent) {
+        type_instance_init(obj, ti->parent);
+    }
+
+    for (i = 0; i < ti->num_interfaces; i++) {
+        type_instance_interface_init(obj, &ti->interfaces[i]);
+    }
+
+    if (ti->instance_init) {
+        ti->instance_init(obj);
+    }
+}
+
+static GHashTable *global_object_table;
+
+void type_initialize(void *data, const char *typename, const char *id)
+{
+    TypeImpl *ti = type_get_instance(type_get_by_name(typename));
+    TypeInstance *obj = data;
+
+    g_assert(ti->instance_size >= sizeof(TypeClass));
+
+    type_class_init(ti);
+
+    g_assert(ti->abstract == false);
+
+    memset(obj, 0, ti->instance_size);
+
+    obj->class = ti->class;
+    snprintf(obj->id, sizeof(obj->id), "%s", id);
+
+    if (global_object_table == NULL) {
+        global_object_table = g_hash_table_new(g_str_hash, g_str_equal);
+    }
+
+    g_hash_table_insert(global_object_table, obj->id, obj);
+
+    type_instance_init(obj, typename);
+}
+
+static void type_instance_finalize(TypeInstance *obj, const char *typename)
+{
+    TypeImpl *ti = type_get_instance(type_get_by_name(typename));
+
+    if (ti->instance_finalize) {
+        ti->instance_finalize(obj);
+    }
+
+    while (obj->interfaces) {
+        Interface *iface_obj = obj->interfaces->data;
+        obj->interfaces = g_slist_delete_link(obj->interfaces, obj->interfaces);
+        type_delete(TYPE_INSTANCE(iface_obj));
+    }
+
+    if (ti->parent) {
+        type_instance_init(obj, ti->parent);
+    }
+}
+
+void type_finalize(void *data)
+{
+    TypeInstance *obj = data;
+    TypeImpl *ti = type_get_instance(obj->class->type);
+
+    g_hash_table_remove(global_object_table, obj->id);
+
+    type_instance_finalize(obj, ti->name);
+}
+
+const char *type_get_name(Type type)
+{
+    TypeImpl *ti = type_get_instance(type);
+    return ti->name;
+}
+
+TypeInstance *type_new(const char *typename, const char *id)
+{
+    TypeImpl *ti = type_get_instance(type_get_by_name(typename));
+    TypeInstance *obj;
+
+    obj = qemu_malloc(ti->instance_size);
+    type_initialize(obj, typename, id);
+
+    return obj;
+}
+
+void type_delete(TypeInstance *obj)
+{
+    type_finalize(obj);
+    qemu_free(obj);
+}
+
+TypeInstance *type_find_by_id(const char *id)
+{
+    gpointer data;
+
+    if (global_object_table == NULL) {
+        return NULL;
+    }
+
+    data = g_hash_table_lookup(global_object_table, id);
+
+    if (!data) {
+        return NULL;
+    }
+
+    return TYPE_INSTANCE(data);
+}
+
+bool type_is_type(TypeInstance *obj, const char *typename)
+{
+    Type target_type = type_get_by_name(typename);
+    Type type = obj->class->type;
+    GSList *i;
+
+    /* Check if typename is a direct ancestor of type */
+    while (type) {
+        TypeImpl *ti = type_get_instance(type);
+
+        if (ti->type == target_type) {
+            return true;
+        }
+
+        type = type_get_by_name(ti->parent);
+    }
+
+    /* Check if obj has an interface of typename */
+    for (i = obj->interfaces; i; i = i->next) {
+        Interface *iface = i->data;
+
+        if (type_is_type(TYPE_INSTANCE(iface), typename)) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+TypeInstance *type_dynamic_cast(TypeInstance *obj, const char *typename)
+{
+    GSList *i;
+
+    /* Check if typename is a direct ancestor */
+    if (type_is_type(obj, typename)) {
+        return obj;
+    }
+
+    /* Check if obj has an interface of typename */
+    for (i = obj->interfaces; i; i = i->next) {
+        Interface *iface = i->data;
+
+        if (type_is_type(TYPE_INSTANCE(iface), typename)) {
+            return TYPE_INSTANCE(iface);
+        }
+    }
+
+    /* Check if obj is an interface and it's containing object is a direct ancestor of typename */
+    if (type_is_type(obj, TYPE_INTERFACE)) {
+        Interface *iface = INTERFACE(obj);
+
+        if (type_is_type(iface->obj, typename)) {
+            return iface->obj;
+        }
+    }
+
+    return NULL;
+}
+
+
+static void register_interface(void)
+{
+    static TypeInfo interface_info = {
+        .name = TYPE_INTERFACE,
+        .instance_size = sizeof(Interface),
+        .abstract = true,
+    };
+
+    type_register_static(&interface_info);
+}
+
+device_init(register_interface);
+
+TypeInstance *type_dynamic_cast_assert(TypeInstance *obj, const char *typename)
+{
+    TypeInstance *inst;
+
+    inst = type_dynamic_cast(obj, typename);
+
+    if (!inst) {
+        fprintf(stderr, "Object %p is not an instance of type %s\n", obj, typename);
+        abort();
+    }
+
+    return inst;
+}
+
+TypeClass *type_check_class(TypeClass *class, const char *typename)
+{
+    Type target_type = type_get_by_name(typename);
+    Type type = class->type;
+
+    while (type) {
+        TypeImpl *ti = type_get_instance(type);
+
+        if (ti->type == target_type) {
+            return class;
+        }
+
+        type = type_get_by_name(ti->parent);
+    }
+
+    fprintf(stderr, "Object %p is not an instance of type %d\n", class, (int)type);
+    abort();
+
+    return NULL;
+}
+
+const char *type_get_id(TypeInstance *obj)
+{
+    return obj->id;
+}
+
+const char *type_get_type(TypeInstance *obj)
+{
+    return type_get_name(obj->class->type);
+}
+
+TypeClass *type_get_class(TypeInstance *obj)
+{
+    return obj->class;
+}
+
+typedef struct TypeForeachData
+{
+    void (*enumfn)(TypeInstance *obj, void *opaque);
+    void *opaque;
+} TypeForeachData;
+
+static void type_foreach_tramp(gpointer key, gpointer value, gpointer opaque)
+{
+    TypeForeachData *data = opaque;
+    data->enumfn(TYPE_INSTANCE(value), data->opaque);
+}
+
+void type_foreach(void (*enumfn)(TypeInstance *obj, void *opaque), void *opaque)
+{
+    TypeForeachData data = {
+        .enumfn = enumfn,
+        .opaque = opaque,
+    };
+
+    g_hash_table_foreach(global_object_table, type_foreach_tramp, &data);
+}
+
+TypeClass *type_get_super(TypeInstance *obj)
+{
+    return type_get_instance(type_get_by_name(type_get_instance(obj->class->type)->parent))->class;
+}
+